Modern telecommunications, optical sensors, lasers and similar systems often use optical fiber links to transmit light between two spatially-separated locations. It is often desired to include different types of photonics devices within such optical fiber links to perform manipulation of the light that is transmitted through the fiber. Such in-line devices may provide thin film filters used in dense wavelength division multiplexing (DWDM) systems, other optical filters and optical spectrum manipulation devices, attenuators, measurement systems, polarizers, in-line light detection and manipulation optoelectronic circuits, sensors, optical isolators, and similar devices that can perform various manipulations of the light propagating along a fiber. Most such devices may tend to be either relatively bulky in size or utilize micro-optical components that are relatively costly to manufacture.
In some systems, the in-line device is integrated within optical fiber. One such well known and widely used in-line fiber device is a fiber Bragg grating. Fiber Bragg gratings can be found in variety of forms and applications, such as in-line sensor for sensing of physical and chemical parameters, in-line optical filters, and other more complex devices, such as dispersion compensators. Fiber Bragg gratings are usually formed by periodic illumination of short section of an optical fiber with ultraviolet light that causes permanent changes in glass structure and thereby its refractive index. Such devices may exhibit large temperature dependence.
Other in-line optical device designs may suffer from considerable optical losses that may limit the optical functions that they can perform. Device fabrication processes may also require assembly of multiple fiber-like optical elements, thereby increasing complexity and cost.
Thus, given the above, it should be recognized that in-line optical devices may be somewhat performance limited, and/or their manufacturing may be relatively complicated. Moreover, they may not be of the same size as the fibers they couple to, i.e., they may be bulky. Accordingly, there is a long felt and unmet need for highly effective, miniature, in-line optical devices and manufacturing methods thereof.